Fig. 1. (A) Schematic representation of the expression strategy. Two transgenic fly lines, one containing a PRC-specific driver and the other containing the open reading frame of the GPCR of interest downstream of a GAL4 UAS, are crossed, and a stable line, containing at least one copy of both transgenes in every generation, is produced. In these flies, developmental factors drive the expression of GAL4, which then activates the expression of the GPCR via the UAS. (B) Schematic presentation of UAS-GPCR and driver-GAL4 lines used in this study. Each receptor was cloned after a GAL4 UAS (green). C-terminal His₆ tag (orange) was added to DmGluRA and V1A. DFz1 contained a myc tag (yellow) in the linker region between the extracellular cysteine-rich domain (CRD) and the seven transmembrane region (7TM, blue) (Boutros et al., 2000). Driver-GAL4 lines used in this study were gmr-GAL4 and rh1-GAL4. (C) Western blot analysis of fly head samples run on a 10% SDS–PAGE. Anti-His₅ antibody (Qiagen) was used to detect DmGluRA and V1A. DFz1 was detected by anti-myc antibody (9E5, Santa-Cruz). DmGluRA run on an SDS–PAGE gel in the presence of 2-mercaptoethanol (βME, 0.7 M) as two different bands corresponding to the sizes of a monomer (*) and a dimer (**). In the absence of βME, only the dimeric form was detected (data not shown). V1A expression was detected in rh1-GAL4; UAS-V1A flies only (∼). Both monomer (+) and dimer (++) DFz1 were detected in gmr-GAL4/UAS-DFz1 flies. Molecular weight markers (kDa) are shown for both blots.